Radiation Safety

Ionising Radiation

The following outlines the requirements for those working with ionising radiation and provides other information that users may find useful.

Key requirements

  • All those involved in the use and management of ionising radiation sources must read the University's Management Procedure which describes how the University manages ionising radiation materials and activities in accordance with  the Ionising Radiation Regulations
  • All new users of ionising radiation must complete a Registration Form for working with ionising radiation (MS Word , 50kb) form before starting work
  • Training: all users of ionising radiation must:
    • attend the University formal training course
    • receive local training specific to their area
  • Prior consent must be obtained from the Departmental Radiation Protection Supervisor before any new apparatus or source which could emit ionising radiation is introduced into the Biology Department
  • Prior consent is required before any new procedure involving the use ionising radiation (e.g. use of open source radioisotopes) begins.  This requires the completion of an Open sources: Risk assessment form (MS Word , 242kb) for each activity.
  • Local rules must be available which describe the hazards and risk reduction measures that must be adopted when using ionising radiation in any area of the department. These rules must be specific to the area where the work is being conducted.

Registration of Ionising Radiation Users

All new users of ionising radiation must be registered.  The Registration Form for working with ionising radiation (MS Word , 50kb)must be completed and signed off by the Group Leader / Supervisor, before forwarding to the Departmental RPS (David Nelson) for approval.

Training

  • All users of ionising radiation must complete the appropriate on-line training modules available on the University Virtual Learning Environment (VLE).  Training modules include a general session to be completed by all users and 3 specialised modules:
    • Working with ionising radiation: GENERAL MODULE
    • Working with ionising radiation: OPEN SOURCES  (unsealed e.g. liquids)
    • Working with ionising radiation: CLOSED COURSES (sealed, encapsulated)
    • Working with ionising radiation: X-RAYS

TO REGISTER FOR THE ON-LINE TRAINING PLEASE CONTACT BIOLOGY’S RADIATION PROTECTION SUPERVISOR (RPS) (DAVID NELSON) STATING WHICH OF THE SPECIALISED SESSIONS YOU NEED TO COMPLETE.

  • Workers can ONLY start activities using ionising radioactive materials after:
    • completing relevant on-line training modules
    • receiving local training from their supervisor (specific experimental procedures) and departmental RPS (includes all general local rules / working practices)
  • It is the responsibility of the supervising academic to ensure that workers in their laboratory work to agreed safety protocols and that proper safety equipment is readily available

Purchase of Open Source Materials

  • Radioisotopes can only be ordered for approved work activities.
  • All radioisotopes must be ordered by authorised persons only.  This will include all supervisors and other persons as nominated on the Nomination for authority to sign for radioactive materials (MS Word , 25kb) form by the supervisor if required.
  • Ordering using Agresso:  authorised persons must select the 'Stable Isotope and Radiochemicals' product code (1LWA01) when placing an order for radiochemicals.
  • Each item ordered will be given a stock card on arrival and the user is responsible for keeping track of the usage, storage and disposal of the material. The stock card must be kept-up-to-date and available for inspection during Safety Audits.
  • The contents of radioactive packages from suppliers should be treated as if they were contaminated. Unpack carefully and monitor the packaging.

Labelling of Open Source Materials

  • The ‘W-Number’ is a unique number given to all stocks of ‘open-source’ radioactive materials brought into the department.  To help easily identify each stock item the stock container must be labelled with this number.  
  • Biology Stores will label the containers of all stocks with this unique ‘W-Number before collection, apart from those materials that are transported on dry-ice.  For these materials, it is the responsibility of the person who placed the order to ensure that the label, provided by Biology Stores, is added to stock container when the stock is unpacked.  Alternatively, the container can be labelled with a black marker pen if the label won’t stick to the container.

Storage of Open Source Materials

Radioisotope stocks and amounts greater than 5MBq should be kept in a lockable container. Dispensed stocks should be kept in proper sealed containers, correctly labelled and securely stored. There is no need to use radioactive stickers on containers holding small amounts of low energy isotopes. If the containers holds less than 0. 1 MBq do not label it. Likewise refrigerators or other areas need not be labelled with radioactive stickers if the amounts contained are less than 1MBq.

Disposal of Open Source Waste

Solid waste

    • 32P or 35S solid waste should be placed in a polythene bag contained in a labelled perspex box and must not be emptied by cleaners.  When two thirds full this should be taken to the locked outside storage areas (E0, next to the E029 Growth Rooms) for storage and decay.  Disposal forms provided must be completed as instructed.  Do not leave radioactive tape or signs on the bag or its contents.   Please contact Lot Doucet to access this facility and for information on the procedure that must be followed when using this storage area.
    • Very low levels of other radioactive materials (typically 14C / 3H / 45Ca) can be placed in the main departmental waste bins (located in the Stores compound area) for collection by the local authority.  Bag(s) of material should be first placed in a black bin liner which must not contain more than 400 kBq (10 µCi) or more than 40 kBq  (1 µCi) in any one item.  All radioactive tape and signs must be removed before disposal. 
    • If the solid waste contains microbiological materials, the waste should be placed in an autoclaved bag and autoclaved before disposal

Liquid aqueous waste

    • Use only designated sinks and do not exceed the stated limits set for each sink (see disposal limits set for each radiation facility in Table 2 below); be sure to check the cumulative limit of the sink you are using. You must record each disposal at the point of disposal on the 'aqueous sink disposal form' provided and also on the item stock record card.

Volatile waste

    • You must not generate gaseous radioactive waste. If you want to generate volatile radioactive waste, you must seek special permission from the University's Radiation Protection Office

Organic scintillate waste

    • They must be kept in special drums available from Biology Stores, such drums being disposed of subsequently via Stores. Each drum must have its own record of disposal sheet to keep track of the items added

Table 1: Disposal limits for the University of York (all in MBq except where indicated)

Isotope

Annual gas

Daily gas

Monthly sink

Annual solid to contractor

Disposal to refuse

Annual Organic

 

3H

Max. of 100
for 3H and 14C

50

125

100

The max amount
is 400KBq
per 0.1 m3
with a max
in any one
item of 40KBq

150

14C

50

43

50

55

32P

NA

NA

128

100

150

33P

NA

NA

100

20

25

35S

NA

NA

200

100

240

45Ca

NA

NA

12

10

15

125I

NA

NA

150

1.2 GBq

NA

Other non alpha emitting isotopes

NA

NA

10

6

6

Table 2: Liquid aqueous waste disposal limits for individual groups within the Department of Biology  

Radiation Facility
Monthly Limits
 

C-14

Ca-45

H-3

I-125

P-32

P33

S-35 

Other

M1

5

-

-

 

30

-

10

 

M0

5

-

10

 

10

-

10

 

L2

-

-

-

60

30

-

10

 

L1

5

-

10

 

-

-

10

 

L0

-

4

5

 

10

4

-

10

D109

-

4

5

 

-

-

-

 

D108

-

-

5

 

-

5

10

 

P53 Laboratory

5

-

10

 

10

8

10

 

F1 (AW/AM)

-

-

10

 

-

-

-

 

F1 (JC)

-

-

-

 

10

-

-

 

IIU

-

3

20

5

20

-

30

 

Teaching Laboratories

10

-

15

 

-

-

5

 

Total

30

11

90

65

120

17

95

10

Radiation Laboratory Requirements

  • All benches should be covered with non-porous, easily cleaned surfaces.
  • Areas designated especially for radioactive work within a laboratory should be indicated with special tape and ideally should be covered with Benchkote or similar material.
  • Dosemeters or contamination/radiation monitors should be provided if required.
  • Clear provision for the correct disposal of waste must be evident.
  • Suitable facilities for hand-washing must be available.
  • A system to monitor the stocks and disposal of the radioisotopes in use must be in place.
  • Designation of laboratories used for ionising radiation:
    • An area is typically designated a controlled area where:
      • the dose rate averaged over a working day exceeds 7.5 µSv h-1
      • if only the hands are exposed, the dose rate averaged over a working day exceeds 75 µSv h-1
      • annual dose to persons is likely to exceed 6 mSv (whole body) or 150 mSv (skin and extremities) or,
      • there is a significant risk of spreading contamination outside the area
    • An area is designated a supervised area where:
      • where conditions need to be kept under review to determine whether it should be designated as a controlled area, or
      • annual dose to persons is likely to exceed 1 mSv (whole body) or 50 mSv (skin and extremities)
    • In laboratories handling modest amounts of radioactive materials, the working procedures are likely to be the same as those required for good laboratory practice- these are not regarded as a specified system of work and the designation of a controlled area should not be necessary.
    • Designation of the laboratory shall be determined after full and proper consultation with the departmental Radiation Protection Supervisor with assistance from the University's Radiation Protection Advisor where necessary.

Local Rules

  • To ensure that radiation doses are kept as low as reasonably practicable (ALARP) it is essential that all persons working with ionising radiation followed agreed methods of working. This information is set out in the Local Rules. These Local Rules should be written by persons experienced in the work being undertaken and must be agreed with the RPS in consultation with the RPA.   
  • A Local Rules Template - Ionising Radiation (MS Word , 55kb) for ‘open source’ radiation areas provides an outline of the basic working practices that must be followed by all individuals working with ‘open-source’ radiochemicals.  It is the responsibility of academic(s) responsible for the area to modify these ‘Local Rules’, as required, to make them specific to the local area and specific activities taking place in this area. 
  • A copy of the Local Rules must be displayed in the area where the work is being carried out and a copy sent to the RPS for approval.
  • Local Rules are intended to focus on the arrangements in a particular area. To be effective the Local Rules should:
    • be brief and concentrate on the activities which give greatest risk
    • focus on the working instructions to be followed by all persons to keep the radiation doses as low as reasonably practicable
    • be local by referring directly to a particular location
    • contain clear instructions which reflect actual working practice
  • Essential contents of Local Rules are:
    • the identification and description of the area covered, with details of its designation
    • the name of the appointed RPS
    • an appropriate summary of the working instructions
    • a copy of the contingency arrangements together with an indication of the reasonably foreseeable accidents to which they relate
  • The Local rules could usefully contain information on the arrangements in that area for:
    • management and supervision of the work
    •  testing and maintenance of engineering controls and design features, safety features and warning devices
    • radiation and contamination monitoring
    • procedures for ensuring staff have sufficient information, instruction and training and
    • procedures for contacting the RPA.
  • Local Rules must be brought to the attention by all those affected by them.

Good Radiation Practice

  • Ingestion of material is prevented by avoiding eating or drinking, hand to mouth contact and mouth pipetting!
  • Wear a fastened lab coat to avoid contamination of skin and clothes
  • Use protective eye-wear and disposable gloves when manipulating solutions or contaminated items.  Gloves offer good spill or splash protection although do not provide shielding protection against  the high energy isotopes such as 32P.  For 3H and 14C, beakers offer better protection.
    • Penetration average for:
      • tritium: air 4mm; water 0.007mm
      • carbon 14: air 28 cm; water 0.3mm; 0.17mm glass
      • phosphorus 32: air 6000mm; water 8mm; 8mm plastic.
      • phosphorus 33: air 450mm; 0.23mm glass.
      • sulphur 35: 430 mm air; 0.5mm plastic; 0.17mm glass.
  • All the normal requirements for Good Laboratory Practice should be followed.
  • It makes sense to limit your exposure to radioactivity in every way possible. Use the minimal amounts necessary for the experiment. Adopt shielding where possible. Spend as little time as possible near the source. Work at arms length from the source if possible.
  • Put on dosemeters or contamination/radiation monitors if required.
  • Ensure that all work is conducted in the correct working area (e.g. liquids handled over trays, gases/aerosols in fume cupboards etc)
  • Be prepared for accidents. Have paper towels at the ready. Have a taped bag ready.
  • Always clean up any spillages immediately, using plenty of paper tissues.
  • Before leaving the laboratory, wash your hands well.
  • When you have finished an experiment, remember to alter the stock record and to fill in the disposal form properly.
  • If possible, use biodegradable, low volatility, safe liquid scintillation counting cocktails. The older, volatile cocktails are not only a bigger fire hazard, they are also more harmful to users is spilled (they were most likely a greater danger than the radioisotopes!)

Ten Golden Rules for Safe Radioisotope Use

  1. Understand the nature of the hazard and get practical training
  2. Plan ahead to minimise exposure time
  3. Keep your distance from the source (doubling the distance quarters the dose)
  4. Use appropriate shielding
  5. Contain the radioactivity within working areas
  6. Wear sensible protective clothing
  7. Monitor contamination frequently
  8. Follow local rules and codes of practice
  9. Minimise waste by using as little as needed and know how to dispose of the waste before you buy the isotope
  10. After work, monitor yourself, the area and wash carefully.

More information is available on the Amersham web site or Amersham products catalogue. They also provide useful information on the safe working practices that should be followed for all the radioisotopes they sell.

Use of 32P

Because of the greater hazards associated with 32P, whenever possible, use 33P in place of 32P. The use of non-radioactive methods of analysis should also be considered. Special rules apply to the use of 32P and those using large amounts must use the special facilities provided in the Department, located on L2.

  • The maximum permitted annual dose limits are 20 mSv. y-1 (body) and 500 mSv. y-1 (hands/skin). If an annual dose 6 mSv y-1 is likely (or doses are likely to exceed 7.5 uSv. h-1) then the work must be conducted in a "controlled" area, and all workers must be "classified".
  • The book "A Practical Approach to the Use of Radiation in Molecular Biology" by Gillian Scott-Wood (H&H Scientific, Leeds, ISBN 0 948237 33 3) provides a very useful guide for users of 32P.  A copy is held by the Departmental Safety Advisor.
  • All reasonable steps to minimise possible contamination with 32Pshould be instigated, particularly direct handling of plastic that comes into contact with 32P. Use proper shielding, between your body and the work area. Buy purpose-made racks to hold vials, Eppendorf tubes, etc. (e.g. see LabLogic).
  • All 32P solid waste must be placed in plastic bags and taken to the 32P waste bins near the Radioactive Waste Storage Room (off E0 corridor), where the activity is left to decay before disposal via the dustbins.

Radioisotope Units and Calculations

  • All calculations and orders must use becquerels (Bq)
  • For those who still think in terms of the late, lamented Curies: 1 µCi = 37 000 Bq (37 kBq)
  • 1Bq is one disintegration per second

Radiation Dose Calculations

Refer to guidance provided in the Open sources: Risk assessment form (MS Word , 242kb)